Mastitis is a common infection ofthe breast during lactation. Mastitis is either infective or due to milk stasis and induces inflammation in the extracellular matrix or stroma of the breast. Mastitis resolves with treatment but causes involution of mammary lobules. Episodes of mastitis are known to increase the risk of breast cancer. Moreover, in the post-lactation period, the breast cancer risk is increased, independent of mastitis. This is in part due to the induction of inflammatory genes during the process of involution. This project aims to determine if breast cancer develops more readily in a post-mastitis milieu. Using high-throughput technologies, we aim to define the acute and chronic changes that mastitis induces in the extracellular matrix (stroma) and how these changes contribute to the formation of breast cancer. Lastly, we aim to define the effects of mastitis on PTHrP signaling in the mammary stroma and PTHrP's role in promoting breast cancer via its effects on mammary stem cells. As a Junior Investigator in the COBRE in Matrix Biology, I will work with my scientific mentor to complete the scientific aims and to develop a grant proposal for future R01 funding.